ABSENCE OF MERKEL CELLS IN LESIONAL SKIN

Background. In vitiligo, other than loss of melanocytes and melanin pigment in the lesional skin, keratinocytes are also Involved. Human fetal Merkel cells are now generally considered to be derived from the epidermis.¹ To date, no observations on Merkel cells in lasional skin of active vitiligo have been reported. Methods. Merkel ceils were identified by indirect immunofluorescence microscopy using the monoclonal antibody TR0MA1. Results. No TROMA 1-positive cells were observed in the vitiliginous skin lesions in any of the specimens examined, whereas normal numbers of these cells were seen in the adjacent pigmented skin. Conclusions. This finding suggests that the processes that lead to damage of keratinocytes in vitiligo also involve other keratin-expressing cells such as the Merkel ceils.     

白癜风表皮黑素细胞超微结构及小眼畸形相关转录因子转录调控研究

目的 研究白癜风黑素细胞超微结构和小眼畸形相关转录因子 （MITF）及其转录调控的酪氨酸酶相关蛋白（TRP）与白癜风临床类型与病程的相关性。方法 选择不同病程的寻常型白癜风（VV）12例和节段型白癜风（SV）8例,分别取白斑区、白斑边缘正常肤色区和远离白斑正常肤色区的表皮片,经组织学确定其表皮的完整性。透射电镜观察10例患者（VV 6例,SV 4例）不同区表皮黑素细胞的超微结构特点。对所有20例远离白斑正常肤色区的表皮片黑素细胞进行培养,应用免疫印迹方法检测 MITF及其转录调控的酪氨酸酶（TYR）、酪氨酸酶相关蛋白1（TYRP1）和酪氨酸酶相关蛋白2（TYRP2）的表达水平。结果 白癜风表皮黑素细胞超微结构病理改变：10例中7例白斑区表皮内未见黑素细胞,1例短病程和2例长病程VV分别可见少量黑素体显著减少或缺失的黑素细胞;白斑边缘正常肤色区,6例VV中,3例病程小于15个月者可见黑素细胞超微结构异常,而4例SV中仅1例异常;远离白斑正常肤色区,10例黑素细胞超微结构均正常。白癜风表皮黑素细胞MITF及其转录调控TRP的表达：VV的MITF表达下调与TYR、TYRP1、TYRP2的表达下调一致;SV存在MITF显著表达下调,而TYR、TYRP1、TYRP2几均正常表达。结论 VV和SV可能存在不同的表皮黑素细胞超微结构病理改变和MITF转录调控机制。     

白癜风患者表皮内郎格罕细胞观察

用改良的Ｊｕｈｌｉｎ－ＳｈｅｌｌｅｙＡＴＰ酶细胞化学染色法检查了１３例白癜风（进展期）患者的白斑、白斑边缘区及对侧相应正常皮肤中郎格罕细胞情况，结果白斑部位表皮郎格罕细胞数目较对应正常皮肤表皮变化不大，而白斑边缘部皮肤郎格罕细胞数目较正常皮肤显著增多（Ｐ＜０．００５）。在白斑及白斑边缘区还可见到印格罕细胞的形态学变化：胞体变大、深染、胞突消失以及细胞积聚现象，在白斑边缘部尤其明显。本研究显示郎格罕细胞数目和形态学的变化与病情活动有关。提示郎格罕细胞在白癜风发病机制中起一定的作用。     

Melanocyte detachment after skin friction in non lesional skin of patients with generalized vitiligo

BACKGROUND: In vitiligo, melanocytes are gradually lost in depigmented macules of the skin. The disappearance of melanocytes has, however, not been clearly observed and consequently the aetiology of the disease (autoimmune, neural, cytotoxic) is still elusive. The starting point of vitiligo macules is frequently determined by local conditions such as wounds and excoriations, but may also follow minor traumas such as pressure or repeated friction. This prominent feature is often neglected. OBJECTIVES: To clarify the biological consequences of repeated friction on the attachment and survival of melanocytes in non lesional vitiligo skin. METHODS: Light reproducible skin friction was performed for 4 min on the volar forearm of 18 patients with extensive vitiligo and five controls with normal healthy skin. Biopsies from the test area and control skin were taken at 1, 4, 24 and 48 h following friction. Serial sections were examined with standard light microscopy, transmission electron microscopy, histochemistry and immunohistochemistry (dihydroxyphenylalanine, HMB-45, E-cadherin and an early apoptosis marker, M30 cytoDEATH antibody). RESULTS: The observation of sections at 1 and 48 h after friction on vitiligo skin and at all time points in controls revealed no changes. In contrast, in vitiligo skin at 4 and 24 h after friction, several melanocytes had undergone detachment and were found in various suprabasal positions, including the stratum spinosum, granular layer, and within and outside the stratum corneum. CONCLUSIONS: Detachment and transepidermal elimination of melanocytes following minor mechanical trauma in non lesional vitiligo skin is probably the cause of depigmentation occurring in the isomorphic response (Koebner phenomenon). We propose that transepidermal elimination of melanocytes in vitiligo should be regarded as a possible mechanism of chronic loss of pigment cells, perhaps previously damaged by another process.     

白癜风患者血浆与皮肤组织液β-内啡肽水平测定

目的 探讨β-内啡肽在白癜风发病中的作用。方法 以125I放免药盒检测了40例白癜风患者血浆及其中33例患者皮肤组织液β-内啡肽水平。结果 白癜风泛发型(11.74±3.47pmol/L,以下单位同)、局限型(8.31±2.57)与节段型(8.61±2.61)患者血浆β-内啡肽水平明显高于正常对照组(6.69±1.46).局限型与节段型白癜风皮损处皮肤组织液β-内啡肽水平(分别为9.25±4.49,10.24±4.37)明显高于非皮损处(分别为5.50±2.84,6.12±1.61).泛发型患者皮损处与非皮损处组织液β-内啡肽水平均有升高,二者差异无显着性。结论 β-内啡肽可能在白癜风的发病过程中起一定作用。     

Role of In Vivo Reflectance Confocal Microscopy in Determining Stability in Vitiligo: A Preliminary Study

Background:

Vitiligo is an acquired pigmentary disorder. In vivo reflectance confocal microscopy (RCM) reproducible imaging technique has already been reported to be useful in the diagnosis of other skin diseases.

Objective:

To define RCM features of vitiligo on different clinical stages.

Materials and Methods:

A total of 125 patients with a clinical diagnosis of vitiligo were included in this study. After informed consent, lesional skins of those vitiligo patients were characterized by using RCM. Five patients with inflammatory cell infiltration observed at the edge of skin lesions and another 5 patients without inflammatory cell infiltration were selected. Biopsies were performed at same sites of the RCM examination areas for histological and immune-histological analysis.

Results:

In the active stage of vitiligo, the RCM examination revealed that the bright dermal papillary rings presented at the dermoepidermal junction level in normal skin lost their integrity or totally disappeared, border between vitiligo lesion and normal skin became unclear, and highly refractile cells that referred to infiltrated inflammatory cells could be seen within the papillary dermis at the edge of the lesions. In the stable stage of vitiligo, the RCM showed a complete loss of melanin in lesional skin and a clear border between lesional and normal skin.

Conclusion:

A simple clinical examination with RCM may reliably and efficiently allow evaluation of the stability status of vitiligo lesions.     

白癜风皮损中NPY VIP和SP的研究

目的 探讨NPY（神经肽Y）、VIP（血管活性肠肽）、SP（神经肽P物质）在白癜风发病机制中的作用。方法 采用SABC免疫组化法对20例白癜风患者（活动期10例，稳定期10例）的皮损、非皮损区以及10例正常人皮肤中的NPY、VIP和SP进行研究，并测定各组皮肤标本中NPY、VIP及SP的免疫反应性。结果 活动期白癜风皮损中NPY、VIP及SP的免疫反应性明显增强，与正常对照及未受累皮肤比较差异有差异性，NPY与SP的反应在白癜风活动期皮损与稳定期皮损比较差异也有显著性。VIP的免疫反应性在白癜风活动期皮损与稳定期皮损中相比稍增强，但差异无统计学意义。结论 神经多肽与白癜风的发病有关，尤其与白癜风的活动性有关。NPY和SP可能在白癜风的发病机制中也起一定的作用。     

Gene expression analysis of melanocortin system in vitiligo

BACKGROUND: The melanocortin system in the skin coordinates pigmentation and immune response and could be implicated in the pathogenesis of vitiligo. OBJECTIVES: We aimed to analyze changes in expression of genes involved in skin pigmentation (melanocortin system and enzymes involved in melanin synthesis). METHODS: With quantitative RT-PCR we measured the mRNA expression levels of eight genes from the melanocortin system and two enzymes involved in melanogenesis. RNA was extracted from both lesional and non-lesional skin of vitiligo patients and in non-sun-exposed skin of healthy subjects. RESULTS: POMC (proopiomelanocortin) expression was lower in lesional skin compared to non-lesional skin. Expression of melanocortin receptors was increased in unaffected skin of vitiligo patients compared to healthy subjects and decreased in lesional skin compared to uninvolved skin of vitiligo patients, the differences were statistically significant in the cases of MC1R (melanocortin receptor 1) and MC4R (melanocortin receptor 4). TRP1 and DCT genes were down-regulated in lesional skin compared to non-lesional vitiligo skin or skin of healthy controls and up-regulated in uninvolved vitiligo skin compared to healthy control samples. In non-lesional skin, POMC expression was not elevated, possibly indicating that systemic influences are involved in up-regulation of MC receptor genes. Decreased expression of the analyzed genes in the lesional skin is not surprising, but statistically significant increased expression of studied genes in non-lesional skin from vitiligo patients is not described previously. CONCLUSION: In our mind, up-regulation of melanocortin system in non-lesional skin could be systemic compensation to restore normal pigmentation in lesions.     

Anti-oxidant defence mechanism in vitiliginous skin increases with skin type

Background Vitiligo skin shows different burning capacity in people with different phototype. In normal skin antioxidant status is correlated to skin phototype, but unexpectedly it appears that there is a gradual decrease in burning susceptibility of depigmented skin of individuals with increasing phototype (II→VI). Objective To assess if the antioxidant response in the lesional vitiligo skin is involved in those protection mechanisms. Moreover, a possible correlation between cutaneous and systemic endogenous antioxidants in vitiligo patients has been investigated. Methods We enrolled in the study 29 patients with active vitiligo, divided into five groups according to skin type (II to VI). We analysed reduced and oxidized glutathione (GSH and GSSG, respectively), ubiquinone (CoQ10), catalase (Cat), superoxide dismutases (Cu/Zn‐SOD and Mn‐SOD), GSH peroxidase (GSH‐Px), as indexes of chemical and enzymatic antioxidants, in suction blister roofs as well as in peripheral blood mononuclear cells (PBMNCs). Results The vitiligo patients showed an imbalance of antioxidant network, both in depigmented skin and PBMNCs. Interestingly, in vitiligo skin a phototype‐related increase of antioxidant enzyme activities (Cat, Mn‐SOD and GPx) and GSH amount have been observed. Similarly in PMBNCs Cat and total SOD activities, as well as GSH content progressively increased from skin type II to skin type VI. Endogenous antioxidants in vitiligo skin are correlated to those in PBMNCs, suggesting that systemic and epidermal antioxidant network functionalities are connected. Conclusions The correlation between antioxidant levels and clinical phototype confirmed the hypothesis that other factors than melanin determine largely the minimal erythema dose values in vitiligo lesional skin.     

Excellent color-matched repigmentation of human vitiligo can be obtained by mini-punch grafting using a machine in combination with ultraviolet therapy

A new method is reported here for treatment of vitiligo by using mini-punch grafting using a machine (mMG) in combination with ultraviolet light B (UVB) therapy. After UVB had been repeatedly irradiated to the lesional facial skin of a patient for 1 month, many mini-punch grafts were removed from the lesional skin and the same numbers of punch biopsies taken from normal scalp skin were placed into the holes of the recipient skin. Repigmentation started soon, and excellent color-matched repigmentation was observed after 12 months. Our easy and speedy mMG seems to be useful for treatment of vitiligo.     

Over-expression of tumor necrosis factor-α in vitiligo lesions after narrow-band UVB therapy: an immunohistochemical study

There is a growing evidence that cytokines are important in the depigmentation process of vitiligo, however, the exact mechanism is not fully understood. The aim of this work was to study the possible role of the tumor necrosis factor-?? (TNF-??) cytokine in the depigmentation process of the disease. Twenty patients with generalized vitiligo were exposed to narrow-band ultraviolet B (NB-UVB) therapy thrice weekly for a total of 60 sessions. Immunohistochemical examination was done, to assess the TNF-?? expression in lesional and perilesional skin as compared to normal control skin, before and after therapy. At baseline, positive lesional TNF-?? expression was detected in 60?% of patients which was significantly higher as compared to perilesional skin (20?%) and negative expression in healthy control skin. Post-treatment, a statistically significant increase in TNF-?? expression was detected in both lesional (90?%) and perilesional skin (70?%) as compared to baseline (P?<?0.05). The significant increase of TNF-?? in vitiligo lesions compared with perilesional and healthy skin suggests a possible involvement of this cytokine in the depigmentation of vitiligo. The increase in TNF-?? expression after NB-UVB phototherapy suggests another role in repigmentation.     

Regulatory T‐cell cytokines in patients with nonsegmental vitiligo

In the etiopathogenesis of vitiligo, the role of suppressor cytokines, such as transforming growth factor‐β (TGF‐β) and interleukin‐10 (IL‐10), associated with regulatory T‐cells (Treg) is not completely known. In this study, the role of Treg‐cell functions in the skin of patients with nonsegmental vitiligo was investigated. Lesional and nonlesional skin samples from 30 adult volunteers ranging in age from 18 to 36 years with nonsegmental vitiligo were compared with normal skin area excision specimens of 30 benign melanocytic nevus cases as controls. All samples were evaluated staining for forkhead box P3 (Foxp3), TGF‐β, and IL‐10 using the standardized streptavidin–biotin immunoperoxidase immunohistochemistry method. Foxp3 expression was lower in lesional vitiligo skin specimens compared to controls; it was also lower in lesional vitiligo specimens than nonlesional vitiligo specimens. IL‐10 levels were lower in lesional vitiligo specimens compared to the controls, whereas IL‐10 expression was significantly lower in lesional specimens compared with nonlesional specimens. TGF‐β expression was higher in both lesional and nonlesional skin specimens of patients with vitiligo compared to controls. TGF‐β expression was lower in lesional skin specimens than nonlesional skin specimens. In addition, there was no significant correlation between Foxp3 expression with TGF‐β and IL‐10 expressions in lesional skin specimens in the vitiligo group. In this study, results supporting the contribution of Treg cells and IL‐10 deficiency to the autoimmune process were obtained. Therefore, future studies are necessary to demonstrate the definitive role of Treg‐cell functions in the etiopathogenesis of vitiligo.     

Role of interleukin-17 in the pathogenesis of vitiligo

Background. Skewing of the immune response towards T helper (Th)1 or Th17 and away from regulatory T cells (Tregs) and Th2 cells may be responsible for the development and progression of autoimmune disease. An autoimmune theory has been proposed in the pathogenesis of vitiligo. No previous reports have investigated alterations in IL‐17 produced by Th17 cells in lesional skin in vitiligo. Aim. To investigate the role of IL‐17 in the pathogenesis of vitiligo by assessing its levels in lesional skin and serum of patients with vitiligo compared with controls. Methods. In total, 30 patients with vitiligo and 20 controls matched for age and gender were enrolled in the study. Serum and tissue IL‐17 levels were measured by ELISA and compared between both groups for correlations with age, gender, family history, disease duration, activity of vitiligo and percentage of involved body surface area. Results. A significant difference between patients and healthy controls was found for both serum and tissue IL‐17 levels (P < 0.001 for both). Significant positive correlations were found between disease duration and IL‐17 level in both serum (r = 0.42, P = 0.02) and lesional skin (r = 0.45, P < 0.015); between extent of vitiligo and IL‐17 levels in both serum (r = 0.65, P < 0.001) and skin (r = 0.48, P < 0.05); and between the serum and the tissue IL‐17 levels in patients with vitiligo (r = 0.54, P = 0.002). Conclusions. Multiple factors have been implicated in the pathogenesis of vitiligo. The increased levels of IL‐17 we found in serum and lesional skin suggest an important role for this cytokine in the pathogenesis of vitiligo.     

Neuropeptide and neuronal marker studies in vitiligo

Neuropeptide and neuronal marker immunoreactivity was studied in skin biopsies from lesional and marginal areas in 12 patients with vitiligo, and in seven normal controls. The vitiligo was active in seven, static in two, and of unknown activity in three. Antibodies against general neuronal marker PGP 9.5 (PGP 9.5), substance P (SP), calcitonin gene-related peptide (CGRP), vasoactive intestinal polypeptide (VIP), and neuropeptide Y (NPY), were used. The epidermis, dermo-epidermal junction, papillary and reticular dermis, and appendages, were assessed semiquantitatively for reactivity with each antibody. Staining with PGP 9.5 in the upper dermis was assessed quantitatively by image analysis. An increase in reactivity against NPY antibody was seen in five of 10 cases (three with active vitiligo) in the marginal areas, and in three of 12 subjects (all with active vitiligo) in the lesional vitiligo areas. VIP antibody reactivity showed a minimal increase in the marginal and lesional vitiligo areas (in two cases each, both of whom had active vitiligo), SP and CGRP reactivities did not differ from normal. PGP 9.5 staining was minimally increased at the dermo-epidermal junction and lower Malpighian layer in biopsies from marginal areas in three of 10 subjects (all with active vitiligo). Quantitative analysis of PGP 9.5 reactivity in the upper dermis showed no difference between vitiligo and normal biopsies. These findings support the concept of neuronal or neuropeptide involvement in vitiligo, and in particular suggest that NPY may have a role in the pathogenesis of the disease.     

Study of CCN3 (NOV) and DDR1 in normal melanocytes and vitiligo skin

We have hypothesised that melanocytes disappear in vitiligo because they are weakly attached to the epidermal basal membrane (melanocytorrhagy). In the epidermis, attachment of melanocytes to collagen IV is mediated through DDR1, which is under the control of CCN3. DDR1 genetic variants have been associated with vitiligo in patients of different ethnic origin. In vitro studies have shown that inhibition of CCN3 induces the detachment of melanocytes. We have studied in parallel the expression of CCN3 and DDR1 in lesional and perilesional skin of patients with vitiligo and the impact of the silencing of CCN3 and DDR1 in normal human melanocytes on their behaviour in epidermal reconstructs. Our in vivo study provides evidence of a dysregulation of the DDR1-CCN3 interaction in vitiligo skin as melanocytes remaining in perilesional skin did not express CCN3. Expression of DDR1 was decreased in lesional versus perilesional vitiligo skin in the majority of patients, and the expression of collagen IV was found decreased in all patients. Silencing of CCN3 in melanocytes induced a significant inhibition of cell adhesion to collagen IV whereas melanocytes transduced with shDDR1 still adhered well on collagen IV and did not increase melanocyte loss in epidermal reconstructs as compared with normal melanocytes. Melanocyte detachment was observed but not in all reconstructs using CCN3 silenced melanocytes. Overall, our study confirms that a downregulation of CCN3 is implicated in melanocyte adhesion in part through DDR1. In vitiligo skin, the interaction of CCN3 with other molecules, such as TGFβ and CCN2, needs to be addressed.     

Involvement of non‐melanocytic skin cells in vitiligo

Despite melanocytes are the key players in vitiligo, a continuous cross‐talk between epidermal and dermal cells may strictly affect their functionality, in both lesional skin and non‐lesional skin. Focusing on this interplay, we have reviewed existing literature supporting evidence on cellular and functional alterations of surrounding epidermal keratinocytes, extracellular matrix (ECM) proteins and fibroblasts in the underlying dermal compartment that may contribute to melanocyte disappearance in vitiligo. We have also examined some clinical and therapeutic aspects of the disease to sustain the non‐exclusive involvement of melanocytes within vitiligo. As a result, a different and more complex scenario has appeared that may enable to provide better understanding about origins and progress of vitiligo and that should be considered in the evaluation of new treatment approaches.     

Motor nerve conduction velocity is affected in segmental vitiligo lesional limbs

To evaluate the effects of segmental vitiligo (SV) on nerve conduction velocity (NCV) in different nerves, we compared the patient's lesional side of their body to the contralateral normal side. The 106 participants were selected from outpatients visiting the dermatological clinics of Huashan Hospital, Fudan University, from November 2011 to March 2014. NCVs were measured on the limbs and the face, including both motor and sensory nerves. The parameters for NCVs included motor nerve conduction velocity (MCV) and its distal conduction latency, sensory nerve conduction velocity, sensory nerve action potentials amplitude, and compound muscle action potential amplitude. MCV on the limbs was compromised by SV state, which was significantly slower on the lesional side of the body compared with the normal contralateral side (P = 0.006). Furthermore, SV at the stable stage significantly impaired MCV compared with the SV at progressive stage. There was no significant difference in the other parameters of NCV between lesional and normal sides of the body. Compound muscle action potentials in the face did not differ between lesional and healthy sides. Motor nerves in the limbs were compromised by SV, particularly when the disease was at the stable stage.     

Assessment of gene expression levels of proopiomelanocortin (POMC) and melanocortin‐1 receptor (MC1R) in vitiligo

Proopiomelanocortin (POMC) and melanocortin 1 receptor (MC1R) are regulators of melanogenesis and pigmentation. Our objective was to estimate their levels, searching for a possible role of the melanocortin system in vitiligo. This study included 40 vitiligo patients and 40 controls. Skin biopsies were taken from lesional and non‐lesional skin of patients and from the non‐sun exposed skin of controls to detect the expression of POMC and MC1R using quantitative real‐time polymerase chain reaction. Both factors were significantly lower in lesional than non‐lesional skin and controls, while they were significantly higher in non‐lesional skin than in controls. There was a statistically significant positive correlation between lesional levels of POMC and MC1R, as well as between non‐lesional levels of POMC and MC1R in the patients. On the other hand, we found a statistically significant negative correlation between the lesional and non‐lesional levels of POMC, as well as between the lesional and non‐lesional levels of MC1R in the patients. As a conclusion, the melanocortin system could play a role in the pathogenesis of vitiligo or could be affected as the end result of the disease.     

The perilesional skin in vitiligo: a colorimetric in vivo study of 25 patients

Background: The aim of this work was to study in vivo the perilesional skin in vitiligo with a colorimetric method. Methods: Twenty‐five patients affected by vitiligo were included. For each patient, three different areas were considered: the lesional, the perilesional and the normal skin as far as 5 cm from the nearest vitiligo spot. Skin pigmentation measurements were performed with a chromameter. Results: The results showed that luminance L^* decreased significantly in relation to increasing distance from the vitiligo spot. As expected, L^* in the vitiligo spot was significantly higher than in the perilesional (P<0.0001) and normal skin (P<0.0001). There was a small difference in L^* between normal skin as far as 5 cm from the nearest vitiligo spot and perilesional skin. In contrast, the pigmentation index (b^*) gradually increased from lesional to perilesional to normal skin. Furthermore, the comparison of the b^* value between the normal skin as far as 5 cm from the nearest vitiligo spot was higher than perilesional skin and it was statistically significant (P<0.0001). Conclusion: Our results in vivo underline that the perilesional skin near the vitiligo spot is lighter than normal skin as far as 5 cm from the vitiligo spot.     

In vivo reflectance confocal microscopy imaging of vitiligo,nevus depigmentosus and nevus anemicus

Background/purpose: Hypopigmentary skin disorders such as vitiligo, nevus depigmentosus and nevus anemicus are common diseases in clinic. The lesions of these diseases could be similar to some extent, although each of them has its own characteristic clinical appearance and histological features. Clinically, the atypical lesions are often difficult to be differentiated. In vivo reflectance confocal microscopy (RCM) is a non‐invasive, repetitive imaging tool that provides real‐time images at a nearly cellular histological resolution. Our aim was to investigate the RCM features of vitiligo, nevus depigmentosus and nevus anemicus. Subjects and Methods: A total of 135 patients with a clinical diagnosis of the aforementioned diseases were included in this study. The RCM images from depigmented skin, border of the white macules, adjacent normal‐appearing skin and distant normal skin for all patients at the dermo‐epidermal junction (DEJ) level were investigated. Results: In the active phase of vitiligo (AVP), the RCM demonstrated a complete loss of melanin in lesional skin in eight (53; 15.1%) patients. In 45 patients (53; 84.9%) of the AVP, part of the bright dermal papillary rings normally seen at the DEJ level disappeared or part of the rings lost their integrity and the content of melanin decreased obviously. In 20 patients (53; 37.7%) of the AVP, highly refractile inflammatory cells could be seen within the papillary dermis in the lesional and adjacent normal‐appearing skin, which may indicate the lesion progresses. In addition, part of the dermal papillary rings showed lack of integrity or their brightness decreased in adjacent normal‐appearing skin in all the patients of the AVP. It is important to know that the RCM demonstrated an ill‐defined border. In the stable phase of vitiligo (SPV), the RCM demonstrates a complete loss of melanin in lesional skin and a clear border in 31 (41; 75.6%) patients; the content of melanin and dermal papillary rings in adjacent normal‐appearing skin show no changes. In 10 (41; 24.4%) patients, the dendritic and highly refractile melanocytes arose in the recovery phase of vitiligo, which may indicate the repigmentation of vitiligo. There are three kinds of repigmentation patterns under RCM: marginal, perifollicular and diffuse. Distant normal skin showed no difference from controls in both the active and the SPV. In all the patients with nevus depigmentosus, the content of melanin decreases obviously but the dermal papillary rings are intact. The dermal papillary rings show no differences between lesional skin and adjacent normal‐appearing skin of nevus anemicus. Conclusion: Considering our results, RCM may be useful to non‐invasively discriminate vitiligo, nevus depigmentosus and nevus anemicus in vivo.